How to change the page order in a PDF
- Tap Choose a PDF to reorder and pick the document.
- Give the new order: typing 3, 1 puts page three first and page one behind it.
- Tap Save new order.
- Open the result and check the first and last pages before you send it anywhere.
An incomplete order moves pages, it never deletes them
Typing 3, 1 on a five-page document means move page three to the front and page one behind it. The three pages you did not name follow in the order they already had, so a five-page document is still five pages afterwards. A tool that read that instruction as keep only these two would throw three pages away without saying anything, and that is not what anybody means by reorder.
Naming the same page twice is allowed rather than rejected, because putting one sheet in two places is a real thing people need — a signature page that belongs at the front and again at the back, for instance.
Moving a page does not re-scan it
Each page travels as it is. Its content is copied without being decoded and drawn again, so a photographed sheet loses nothing, text stays selectable and searchable, and the page size and any rotation already stored on that page come along with it.
Bookmarks are the exception and they do not survive. The document is written fresh, and an outline whose destinations have all moved would send readers to the wrong pages, so it is dropped and you are told when your file had one. Form answers stay on the page as printed text.